Phenylacetaldehyde reductase (PAR) is suitable for the conversion of various aryl ketones and 2-alkanones to corresponding chiral alcohols. 2-Propanol acts as a substrate solvent and hydrogen donor of coupled cofactor regeneration during the conversion of substrates catalyzed by PAR. To improve the conversion efficiency in high concentrations of substrate and 2-propanol, selection of a PAR mutant library and the subsequent rearrangement of mutations were attempted. With only a single selection round and following the manual combination of advantageous mutations, PAR was successfully adapted for the conversion of high concentrations of substrate with concentrated 2-propanol. This method will be widely applicable for the engineering of enzymes potentially valuable for industry.